Printer paper roll holder with spring-controlled line feed tensioner

ABSTRACT

A composite paper roll holder and line-feed tensioner comprises a specially configured wire bail, which provides both paper rollsupporting spindles and a paper tensioning guide rod, and a pair of spaced and pivotally mounted paper holder arms, each arm having a spindle receiving slot and a second slot adjacent thereto so as to form an integral tooth-like spring therebetween. The springs are dimensioned so as to periodically bias the bail and, thereby, provide controlled paper tensioning in response to and in a manner correlated with, each line-feed advancement of the paper.

United States Patent 1191 Denley 1 Sept. 30, 1975 1 41 PRINTER PAPER ROLL HOLDER wl'm 3.797.631 3/1974 Crone 197 133 R SPRINGCONTROLLED LINE FEED 3.810.536 5/1974 Madore 197/133 R TENSIONER FOREIGN PATENTS OR APPLICATIONS [75] Inventor: Ronald S. Denley, Niles. 111. 304.737 4/1955 tze land 97/133 R [73] Assignee: Teletype Corporation, Skokie, I11.

Primal/'1- Exm71iner-Ernest T. Wright. Jr. 22 F1 d. 19 1974 l 1 16 June Attorney, Agent, or Firm-K. R. Bergum; .l. D. pp Flo-14801785 Kaufmann; J. L. Landis [52] [1.5. CI. 197/133 R [51] Int. Cl. B41J 15/00 7 [58] Field of Search 197/132, 133 R, 134, 180; 1571 ABSTRACT 281/11; 226/195, 196. 197, 198, 199 A composite paper roll holder and line-feed tensioner comprises a specially configured wire bail, which pro- [56] References Cited vides both paper roll-supporting spindles and a paper UNITED STATES PATENTS tensioning guide rod. and a pair of spaced and pivot- 4460 22/189] Pickles H 97/123 R X ally mounted paper holder arms, each arm having a i H1893 Gillespie l97/153Rx spindle receiving slot and a second slot adjacent 2. 9/1905 Bright I U 197/1 3 R thereto so as to form an integral tooth-like spring 840,334 1/1907 s i L 197 133 R therebetween. The springs are dimensioned so as to 1.158.519 11/1915 Lotterhand. 197/133 R periodically bias the bail and, thereby. provide con- 1.248,677 12/1917 LaMoy 197/13 R trolled paper tensioning in response to and in a manl-503-031 7/1924 Brown 1 197/133 R ner correlated with, each line-feed advancement of 1.539.994 6/1925 Cooper 281/11 the pap 1.571.786 2/1926 Birmingham... 197/133 R 3.793.951 2 1974 Denley 197/133 R x 9 Claims. 6 Drawing Figures U.S. Patent Sepfi. 30,1975

PRINTER PAPER ROLL HOLDER WITH SPRING-CONTROLLED LINE FEED TENSIONER BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper roll holder and tensioner and, more particularly, to a composite paper roll holder and spring-controlled line feed tensioner applicable for use with printers.

2. Description of the Prior Art In the successive line feed advancement of a web, such as paper in roll stock form, on which printing is to take place, a separate springbiased paper guide rod or bar has often been employed to provide a predetermined degree of resiliency in the paper whenever it is abruptly drawn from the roll thereof. This built-in resiliency, or paper tensioning, is employed to prevent the possibility of the paper either tearing, or not advancing a full line space, each time the line feed mechanism of the printer attempts to overcome the inertia effect of the mass of the paper roll. The importance of a springbiased paper tensioner increases directly with the lineprinting rate of the printer, and with the mass of the paper roll, as the more rapid are the advancements of the paper, the more severe is the jerking effect if not compensated for in some way.

Certain prior line feed paper tensioners have also served another important function, namely, to effect an incremental slack-producing advancement of the paper from the roll thereof between successive line feeds. To accomplish this the line feed mechanism, in periodically advancing the paper over the tensioner, displaces the latter by an amount sufficient to establish the desired spring-biased counter force in the-springs associated therewith. This counter force is chosen so that upon completion of each line feed, the then biased tensioner will draw an incremental length of paper from the roll thereof, while returning to its normal unbiased position, before the next line feed is initiated by the printer. Thus, each time the line feed mechanism is actuated, it is presented with an initial predetermined amount of slack in the paper, which helps to cushion the inertia effect of the paper roll.

Prior paper line feed tensioners have generally comprised a yieldable guide rod that has been mounted in a manner that in no way contributed to the support of the paper roll itself, and which guide rod typically has been spring-biased by auxiliary coil springs connected SUMMARY OF THE INVENTION It, therefore, is an object of the present invention to provide a new and improved composite paper roll holder and spring-controlled line feed tensioner which substantially minimizes the number of parts required,

and greatly simplifies the assembly thereof.

In accordance with the principles of the present invention the above and other objects are realized by the present novel paper roll holder and tensioner. The holder and tensioner includes a pair of arms mountable to supporting structure, for example, the housing of a printer. Each arm has formed therein a pair of spaced slots which pass through one edge thereof. The slots define an integral, tooth-like resilient member of predetermined resiliency therebetween. The holder and tensioner also includes a bail. The bail has two elongated parallel leg portions which depend or extend away from an intermediate leg portion. The intermediate leg portion is ultimately positioned to be contacted by the sheet material which passes thereover as it is removed from the roll. The free end of each of the depending leg portions is U-shaped and the spacing between the parallel segments of each U is dimensioned so that each segment pair may be respectively received in one of the slots of each slot pair. Specifically, the parallel segments of the Us are received respectively in the slot which is rearward from the other slot with respect to the direction of removal of the sheet material from the roll. One of the parallel segments in each U has a free end. The free ends are mutually opposed and are axially aligned to rotatably support the roll of sheet material therebetween.

Further, in accordance with the principles of the present invention, the above and other objects are realized in one preferred illustrative embodiment wherein a paper roll holder incorporating line feed tensioning comprises a pair of spaced bracket-like paper holder arms, and a specially configured spindle and tension rod functioning wire bail. Each arm is adapted for piv otal mounting at one end to a back support plate, such as the back wall of a printer housing, and has a first inclined slot formed therein which communicates with the upper edge of the associated arm, as mounted, and supports at the base thereof a spindle end of the wire bail.

The specially configured wire bail has two spaced, elongated and parallel extending leg portions which merge into an outwardly extending intermediate leg portion which functions as a spring-biased paper tensioning guide rod. The bail also has a U-shaped section formed near the lower end of each parallel extending leg portion, with the parallel segments thereof being dimensioned so that they are both received within the aforementioned slot of the associated arm. The lower terminating segments of the two U-shaped sections are mutually opposed and axially aligned so as to define the aforementioned spindles on which rotatable hubs are mounted, the latter supporting a roll of paper by and at the ends of a central core thereof.

In accordance with an aspect of the invention, a second inclined slot is also formed in each paper holder arm, nearer the pivotally mounted end thereof, at a predetermined angle and spacing relative to the first slot so as to form an integral tooth-like spring therebetween, exhibiting a known degree of resiliency. As a result of the paper being periodically advanced over the outwardly extending intermediate leg portion of the bail, in the direction of the printer, the upper short horizontal segment of each U-shaped section of the bail is biased against the upper free end of the tooth-like spring associated therewith.

Thus, as the line feed mechanism of a printer, for example, advances the paper from the roll during each periodic line feed, the cantilevered, intermediate leg portion of the bail is spring-biased in an arc in the general direction of paper advancement, with the upper segment of each U-shaped section of the bail deflecting the tooth-like spring of each associated paper holder arm in the direction toward the second slot formed therein.

This periodic deflection of the tooth-like springs thereafter results in periodic deflection-dependent forces (through recoil action) being imparted by the springs against the wire bail so as to control and correlate the desired alternate tensioning of and slack developed in the paper for each line feed advancement thereof. Considered another way, once the tooth-like springs of the paper roll holder arms have been deflected by the desired amount during each line feed advancement of the paper, the then established bias forces exhibited by the springs will thereafter tend to pivot the wire bail through a small arc in the opposite direction which, in turn, will draw an incremental length of paper off the roll before the next line feed commences. As such, the line feed mechanism advantageously is always presented with a predetermined degree of slack in the paper at the start of each line feed advancement thereof.

The integral tooth-like springs formed in the paper holder arms also give rise to further advantages in that they require no additional material or assembly costs, involve no periodic adjustment, and require no additional space either within or without the printer housing. In addition, the paper holder arms, by being hinged to the rear wall of the printer housing (or any other suitable support member), may advantageously be folded inwardly when not in use after the wire bail has been removed so as to be positioned flush with the support structure therefor. Detents formed in the arms also allow them to be removably locked in such a folded position so as to facilitate handling or transport of the printer.

BRIEF DESCRIPTION OF THE DRAWING.

FIG. 1 is a partially broken away perspective view of an illustrative printer, showing a composite paper roll holder and spring-controlled line feed tensioner applicable for use therewith and embodying the principles of the present invention;

FIG. 2 is an enlarged rear elevational view, taken generally along the line 2-2 of FIG. 1, showing details of the composite paper roll holder and springcontrolled tensioner;

FIG. 3 is an enlarged, side elevational view taken along line 3-3 of FIG. 2 and showing of one paper roll holder arm and a portion of the wire bail tensioner associated therewith as mounted on the rear wall of a printer;

FIGS. 4 and 5 are enlarged, fragmentary, side elevational views, partially in section, and taken along line 44 of FIG. 2 illustrating in detail the slotted portion of one paper roll holder arm, and the normal and deflected positions, respectively, of the integral tooth-like spring thereof, the latter position being in response to a line feed initiated pivoted deflection of the wire bail; and

FIG. 6 is a fragmentary plan view, taken along the line 6-6 of FIG. 4, showing in detail a portion of the upper edge of one support arm.

DETAILED DESCRIPTION OF THE INVENTION It is understood that the unique paper roll holder with spring-controlled line feed tensioning as embodied herein has universal application in any device wherein sheet material is drawn from a roll thereof but for purposes of illustration, it is disclosed herein in connection with a matrix printer 10 of the type depicted generally in FIG. 1. As the paper roll holder 15 is only associated directly with a rear wall 25 of a housing 11 of the printer 10, few details of the printer per se are required in order to appreciate and fully understand the unique features of the present invention. It will suffice to simply say at this point that most printers, whether of the matrix, impact, or any other type, incorporate a line feed mechanism, such as that generally depicted at 12 in FIG. 1, for periodically advancing a line space length of paper 13 from a roll 24 thereof, for example, by rotating a platen 14 which frictionally engages the paper 13. One preferred printer 10 of the dot matrix type with which the present paper roll holder 15 may be conveniently used is disclosed in a commonly-assigned, copending application of J. L. DeBoo-E. C. Feldy-H. S. Grear, Ser. No. 468,046, filed May 8, 1974, herein incorporated by reference. The line feed mechanism 12 herein is depicted at the reference numeral 53 in the DeBoo et al. application.

With attention now directed to FIGS. 1-3, it is seen that the paper roll holder with spring-biased line feed tensioning is identified generally by the reference numeral 15, and as embodied herein comprises a pair of spaced side or paper holder arms l717, preferably made of a suitable plastic material, and a specially configured wire bail 21. The bail 21 is formed with two spaced and outwardly extending parallel leg portions 21a which are interconnected by an outwardly extending and horizontal intermediate leg portion 21b (see FIG. 3), the latter functioning as a cantilevered, springbiased paper guide rod tensioner, as will be described more fully hereinbelow.

The two mutually disposed lower ends of the leg portions 21a of the bail 21 are each formed into a U- shaped section comprised of two horizontal leg segments 21c and d which are interconnected by an intermediate leg segment 21e. The two leg segments 21:! are mutually opposed and axially aligned (as best seen in FIG. 2) to form spindles upon which suitable hubs 22 are rotatably mounted. The hubs 22, in turn, rotatably support (between flange-formed ends thereof) the lml low core 23 ofa roll 24 of paper 13, or any other record medium in roll stock form on which printing is to take place.

As best seen in FIG. 3, each side or paper holder arm 17 has two mutually disposed and oppositely directed snap-in pin portions which are pivotally secured within mating recesses 17:] in the rear wall 25 of the housing 11 for the printer 10. The end of each paper holder arm 17 near the pin portions 170 is made sufficiently resilient so as to facilitate the snap-in mounting thereof into the aforementioned recesses 17d by forming a central opening 17b between the pin portions 17a. It is understood, of course, that the arms 17 may be adapted for pivotal snap-in mounting on any other suitable support member, or structure, with which the holder 15 is to be associated.

In accordance with the principles of the present invention, the paper holder arms 17 are each formed with a first inclined slot 31 (best seen in FIGS. 3-5), and with a second inclined slot 33, nearer the pin portions 17a. The angle of each slot 31,33 and the spacing therebetween are chosen so as to form an intermediate tooth-like integral spring 35 which exhibits a known degree of resiliency. Such a spring 35 not only obviates the need for any assembly or adjustment operations, but by being formed integrally with each side arm 17, requires no additional material or space.

As best seen in FIGS. 4 and 5, the top of each spring 35 is formed with a hammer-like head, having a front nose portion 35a, a rear portion 35b and a hemispherically shaped or dome portion 350. The front nose portion 35a of the spring 35 is dimensioned so as to prevent the leg segments 21c 21d of the associated U- shaped section 21c, 21d, 21:: of the bail 21 from being accidentally inserted into the slot 33 rather than the intended slot 31 during assembly. The rear portion 35b of the hammer-like head of each spring 35 has an arcuate underside surface 35b which is dimensioned to partially confine the associated horizontal leg segment 210 of the U-shaped section 21c, 21d, 212 after the leg segments 21c, 21d have been inserted into the slot 31; The dome portion 350 of each tooth-like spring 35 is employed to function as a resilient snap-in detent to be received, for example, within a dimpled recess or recess 256 formed in the upperedge a of a rectangularly shaped recessed area 25b in the rear wall 25 of the printer 10. The recessed area 25b is dimensioned to accommodate the side arms 17. As a result, when not in use, the paper holder arms 17 may be folded into a position substantially flush with the rear wall 25 of the housing 11, and removably locked in that position by the detents or dimpled recesses 250 which hold the dome portions 350.

The desired incremental spring-tensioned line feeding of the paper' 13 from the roll 24 is effected in the following manner: After a roll 24 of paper 13 has been supported on the rotatable hubs 22, which are rotatably held by the leg segments 21d the leg segment 21d of each U-shaped section 21c, 21d, 21e of the bail 21 is positioned at the base of the associated slot 31, whereas the upper leg segment 21c is positioned against the arcuate underside surface b'of the spring 35.

Upon a line feed being initiated by the line feed mechanism 12 of the printer 10, the paper 13 in being abruptly advanced in the direction of the arrow 38 in FIGS. 1 and 3, will produce a leveraged pivotal force designated F against the intermediate leg portion 21b of the wire bail 21. This force F in turn, causes the leg segment 21c of each U-shaped section 21c, 21d, 212 to exert a force F,, against the upper end of the associated spring 35. Simultaneously, the leg segment 21d exerts a leveraged force F, in the opposite direction against the side wall at the base of the slot 31.

As a result of such forces, F and F, the bail 21 is pivoted, for example, from the position represented by the dashed line 41 to the position of the dashed line 42 in FIG. 5 after each line feed advancement of the paper 24. At the same time, the springs 35 are also displaced in an essentially pivotal manner from the position depicted in FIG. 4 to the position of Flg. 5. When in the latter position, it is seen that the upper front nose portion 35a of each spring 35 extends into the recessed area 17c but preferably never contacts the inner surface of the recess during line feeding.

Upon completion of a line space advancement 38 of the paper 13, the springs 35 will thereafter attempt to recoil to pivot the bail 21 to its normal position (FIG. 4 and line 41 in FIG. 5), causing an incremental length of the then taut paper 13 to be advanced from the roll 24. Considered another way, the upper intermediate leg portion 21b of the bail 21 in moving back from its spring-biased position (e.g., line 42 in FIG. 5) to the position of line 41, will draw a length of paper 13 from the roll 24 equal to approximately the length of the are 45 through which the intermediate leg portion 21b of the bail 21 moves.

Ideally, the incremental advancement of the paper 13 in response to the recoil action of the springs 35 should be closely correlated with the line-feed advancement thereof. More specifically, each line-feed advancement of the paper 13 should be sufficient to not only take up the previously produced spring-initiated slack in the paper 13, but to again effect the desired pivotal movement of the wire bail 21 required to reestablish the combined requisite spring-biased counter force in the springs 35. When such interrelated paper advancements from the roll 24 take place, it is seen that the line feed mechanism 12 of the printer 10 need not require much driving torque, and the sudden jerking of the paper 13 during line feeding to overcome the inertia effect produced by the mass of the .011 24 of paper 13 is eliminated. This is particularly inportant in high speed printers, as a full roll 24 of paper 13 when subjected to very sudden periodic incremental rotation, could otherwise cause the paper 13 to either tear, or result in less than a full line space advancement of the paper 13, such as due to slippage by the line feed mechanism 12.

In summary, a simple, inexpensive and reliable composite paper roll holder and line-feed tensioner 15 has been described wherein a specially configured wire bail 21 cooperates with a pair of spaced paper holder arms 17, each having an integral tooth-like spring 35 formed therein, to both support a roll 24 of paper 13 and periodically tension the paper 13 in response to, and in a manner correlated with, each line feed advancement thereof.

As the resiliency of the springs 35 may be readily controlled during the manufacture of the side arms 17, by the proper dimensioning thereof, and through the choice of material, they can be specifically made for very demanding and specific applications, as well as for universal use. Once the arms 17 are formed, preferably by an inexpensive molding process, and when made out of a suitable material, such as Delrin plastic, sold by E. I. Dupont deNemours and Company, which plastic exhibits excellent elastic recovery characteristics, the toothlike springs 35 advantageously will retain their resiliency over very long periods of repetitious use. In addition, such uniquely constructed springs 35 are formed with no material or assembly costs over and above those for the side or paper holder arms 17 themselves, and require no additional space.

In view of the foregoing, it is obvious that various modifications may be made to the present illustrative embodiment of the invention, and that a number of alternatives may be provided without departing from the spirit and scope of the invention.

What is claimed is:

1. A paper roll holder and tensioner comprising:

two rectangularly shaped paper roll holder arms, each of said arms being attachable at one end to a support member, and each of said arms having first and second inclined slots formed therein, said slots communicating with the upper edge of the associated arm as attached, and being spaced apart and inclined relative to each other so as to define an integral, tooth-like spring of predetermined resiliency therebetween,

a wire bail having two elongated and parallel extending leg portions which merge into an outwardly extending intermediate leg portion, the lower end region of each parallel extending leg portion being formed into a U-shaped section, with the spacing between the parallel segments thereof being dimensioned so that the parallel segments are both received within the second slot which is furthest from the attachment end of the associated arm, and the lower terminating segments of said U-shaped bail sections being mutually opposed and axially aligned so as to define spindles for rotatably supporting a roll of paper at the ends of a central core thereof.

2. A paper roll holder and tensioner in accordance with claim 1 wherein the tooth-like spring in each arm is formed with both forward and rearward protruding upper end portions, and wherein said slot nearest the one arm end communicates with a recess positioned so that said upper, forward protruding portion of said spring is yieldably displaced at least partially within said recess in response to a force exerted against said spring in the direction of said recess by said wire bail.

3. A paper holder and tensioner in accordance with claim 2 wherein the upper free end of each of said springs is formed with a hemispherically shaped detent for releaseably locking the associated arm against a support member, having a detent-receiving recess, when not in use and folded back thereagainst.

4. In a printer including a housing and means for periodically line-feed advancing an incremental length of a record medium applied in roll stock form on which alphanumeric characters are to be printed, the combination further including:

a record medium roll holder which produces springcontrolled line-feed tensioning comprising:

two thin, substantially rectangularly shaped record medium roll holder arms, each of said arms being made of a plastic material and being pivotally attachable at one end to the printer housing, and each arm having first and second inclined slots formed therein, with the first slot being positioned nearer the pivotal end of said arm, said slots communicating with the upper edge of the associated arm as mounted, and being spaced apart and inclined relative to each other so as to define an integral, tooth-like spring of predetermined resiliency therebetween;

a wire bail having two elongated and parallel extending leg portions which merge into an outwardly extending intermediate leg portion, the lower end region of each parallel extending leg portion being formed into a U-shaped section, with the spacing between the parallel segments thereof being dimensioned so that the parallel segments are both received within the second slot, and the lower terminating segments of said U-shaped bail sections being mutually opposed and axially aligned so as to define spindles; and

rotatable hub means mounted on each of said bail spindles for rotatably supporting a roll of said record medium at the ends of a central core thereof.

5. In a printer including a record medium roll holder which produces line feed tensioning in accordance with claim 4, said tooth-like spring in each arm further being formed with both forward and rearward protruding upper end portions, said forward protruding portion preventing the associated U-shaped section of said bail from being accidentally inserted into said first slot, and said rearward protruding portion, at least in part, confining said associated U-shaped bail section within said second slot.

6. In a printer including a record medium roll holder which produces line feed tensioning in accordance with claim 5, said first slot further having a recess communicating therewith and positioned so that said upper, forward protruding portion of said associated spring is yieldably displaced at least partially within said recess in response to a force exerted against said spring in the direction of said printer by said wire bail, said bail being pivoted in the direction of said printer in re sponse to each line feed advancement of said record medium while being drawn over the intermediate leg portion of said bail.

7. In a printer including a record medium roll holder which produces line feed tensioning in accordance with claim 5, the upper free end of each of said springs further being formed with a hemispherically shaped detent for releaseably locking the associated arm against the printer housing when not in use and folded back thereagainst, said rear wall having a detent-receiving recess formed therein for each arm, and the pivotal end of each of said arms being formed with two mutually opposed pin portions which are separated by a recessed area so as to facilitate the resilient snap-in insertion of said pin portions within accommodating recesses formed in the printer housing.

8. A holder and tensioner for a sheet material roll from which sheet material is removed effecting rotation of the roll on its major axis, the holder and tensioner comprising:

a pair of arms each having therein a pair of spaced slots through an edge thereof, each slot pair defining an integral, tooth-like resilient member therebetween, the resilient members being aligned and parallel to the major axis of the roll when held by the holder and tensioner; and

a bail having two elongated, parallel leg portions de pending from an intermediate leg portion, the free end of each leg portion being U-shaped, the parallel segments of each U-shaped leg portion end being spaced so that said parallel segments are respectively, transversely positionable within one of the slots of each slot pair, which one slot is rearward of the other slot with respect to the direction of removal of the sheet material from the roll, one of the parallel segments of each U-shaped leg portion end having a free end, the free segment ends being mutually opposed and axially aligned to ro tatably support the roll therebetween, the intermediate leg portion of the bail being contactable by the sheet material passing thereover when the parallel segments are positioned in their respective one slot and upon removal of the sheet material from the roll.

9. A holder and tensioner for a sheet material roll from said sheet material is removed effecting rotation of the roll on its major axis, the holder and tensioner comprising:

a bail having two elongated, parallel leg portions depending from an intermediate leg portion, the free end of each leg portion being U-shaped, one of the parallel segments of each U-shaped leg portion end having a free end, the free segment ends being mutually opposed and aligned to rotatably support the roll therebetween; and

a pair of arms each having therein a pair of spaced slots through an edge thereof, each slot pair defining an integral, tooth-like resilient member therebetween, the resilient members being aligned and parallel to the major axis of the roll when held by the holder and tensioner, the one slot of each slot pair which is rearward of the other slot with respect to the direction of removal of the sheet material from the roll being dimensioned to transversely support therein the parallel segments of one of the respective U-shaped leg portion ends, the intermediate leg portion of the bail being contactable by the sheet material passing thereover when the parallel segments are supported in their respective one slot and upon removal of the sheet material from the roll. 

1. A paper roll holder and tensioner comprising: two rectangularly shaped paper roll holder arms, each of said arms being attachable at one end to a support member, and each of said arms having first and second inclined slots formed therein, said slots communicating with the upper edge of the associated arm as attached, and being spaced apart and inclined relative to each other so as to define an integral, tooth-like spring of predetermined resiliency therebetween; a wire bail having two elongated and parallel extending leg portions which merge into an outwardly extending intermediate leg portion, the lower end region of each parallel extending leg portion being formed into a U-shaped section, with the spacing between the parallel segments thereof being dimensioned so that the parallel segments are both received within the second slot which is furthest from the attachment end of the associated arm, and the lower terminating segments of said Ushaped bail sections being mutually opposed and axially aligned so as to define spindles for rotatably supporting a roll of paper at the ends of a central core thereof.
 2. A paper roll holder and tensioner in accordance with claim 1 wherein the tooth-like spring in each arm is formed with both forward and rearward protruding upper end portions, and wherein said slot nearest the one arm end communicates with a recess positioned so that said upper, forward protruding portion of said spring is yieldably displaced at least partially within said recess in response to a force exerted against said spring in the direction of said recess by said wire bail.
 3. A paper holder and tensioner in accordance with claim 2 wherein the upper free end of each of said springs is formed with a hemispherically shaped detent for releaseably locKing the associated arm against a support member, having a detent-receiving recess, when not in use and folded back thereagainst.
 4. In a printer including a housing and means for periodically line-feed advancing an incremental length of a record medium applied in roll stock form on which alphanumeric characters are to be printed, the combination further including: a record medium roll holder which produces spring-controlled line-feed tensioning comprising: two thin, substantially rectangularly shaped record medium roll holder arms, each of said arms being made of a plastic material and being pivotally attachable at one end to the printer housing, and each arm having first and second inclined slots formed therein, with the first slot being positioned nearer the pivotal end of said arm, said slots communicating with the upper edge of the associated arm as mounted, and being spaced apart and inclined relative to each other so as to define an integral, tooth-like spring of predetermined resiliency therebetween; a wire bail having two elongated and parallel extending leg portions which merge into an outwardly extending intermediate leg portion, the lower end region of each parallel extending leg portion being formed into a U-shaped section, with the spacing between the parallel segments thereof being dimensioned so that the parallel segments are both received within the second slot, and the lower terminating segments of said U-shaped bail sections being mutually opposed and axially aligned so as to define spindles; and rotatable hub means mounted on each of said bail spindles for rotatably supporting a roll of said record medium at the ends of a central core thereof.
 5. In a printer including a record medium roll holder which produces line feed tensioning in accordance with claim 4, said tooth-like spring in each arm further being formed with both forward and rearward protruding upper end portions, said forward protruding portion preventing the associated U-shaped section of said bail from being accidentally inserted into said first slot, and said rearward protruding portion, at least in part, confining said associated U-shaped bail section within said second slot.
 6. In a printer including a record medium roll holder which produces line feed tensioning in accordance with claim 5, said first slot further having a recess communicating therewith and positioned so that said upper, forward protruding portion of said associated spring is yieldably displaced at least partially within said recess in response to a force exerted against said spring in the direction of said printer by said wire bail, said bail being pivoted in the direction of said printer in response to each line feed advancement of said record medium while being drawn over the intermediate leg portion of said bail.
 7. In a printer including a record medium roll holder which produces line feed tensioning in accordance with claim 5, the upper free end of each of said springs further being formed with a hemispherically shaped detent for releaseably locking the associated arm against the printer housing when not in use and folded back thereagainst, said rear wall having a detent-receiving recess formed therein for each arm, and the pivotal end of each of said arms being formed with two mutually opposed pin portions which are separated by a recessed area so as to facilitate the resilient snap-in insertion of said pin portions within accommodating recesses formed in the printer housing.
 8. A holder and tensioner for a sheet material roll from which sheet material is removed effecting rotation of the roll on its major axis, the holder and tensioner comprising: a pair of arms each having therein a pair of spaced slots through an edge thereof, each slot pair defining an integral, tooth-like resilient member therebetween, the resilient members being aligned and parallel to the major axis of the roll when held by the holder and tensioner; and a bail having two elonGated, parallel leg portions depending from an intermediate leg portion, the free end of each leg portion being U-shaped, the parallel segments of each U-shaped leg portion end being spaced so that said parallel segments are respectively, transversely positionable within one of the slots of each slot pair, which one slot is rearward of the other slot with respect to the direction of removal of the sheet material from the roll, one of the parallel segments of each U-shaped leg portion end having a free end, the free segment ends being mutually opposed and axially aligned to rotatably support the roll therebetween, the intermediate leg portion of the bail being contactable by the sheet material passing thereover when the parallel segments are positioned in their respective one slot and upon removal of the sheet material from the roll.
 9. A holder and tensioner for a sheet material roll from said sheet material is removed effecting rotation of the roll on its major axis, the holder and tensioner comprising: a bail having two elongated, parallel leg portions depending from an intermediate leg portion, the free end of each leg portion being U-shaped, one of the parallel segments of each U-shaped leg portion end having a free end, the free segment ends being mutually opposed and aligned to rotatably support the roll therebetween; and a pair of arms each having therein a pair of spaced slots through an edge thereof, each slot pair defining an integral, tooth-like resilient member therebetween, the resilient members being aligned and parallel to the major axis of the roll when held by the holder and tensioner, the one slot of each slot pair which is rearward of the other slot with respect to the direction of removal of the sheet material from the roll being dimensioned to transversely support therein the parallel segments of one of the respective U-shaped leg portion ends, the intermediate leg portion of the bail being contactable by the sheet material passing thereover when the parallel segments are supported in their respective one slot and upon removal of the sheet material from the roll. 